Scintigraphic tracking of mesenchymal stem cells after intravenous regional limb perfusion and subcutaneous administration in the standing horse.

The research investigates the effectiveness and challenges of administering radiolabeled mesenchymal stem cells (MSCs) to horses. Techniques of injection included intravenous regional limb perfusion (RLP) and subcutaneous injections. The study found that the techniques used in standing, sedated horses were less effective compared to previously reported procedures performed on anesthetized horses.

Methods

The research involved an experiment with twelve horses. The horses were divided into two groups and each group was subjected to different sets of procedures:

• The first group of six horses underwent RLP through the cephalic vein of one limb and a subcutaneous injection in the metacarpal area of the other limb.
• The other group also had six horses. They underwent RLP through the lateral palmar digital vein of one limb and a subcutaneous injection in the coronary band area of the other limb.

MSCs were tagged with technetium-HMPAO for tracking via scintigraphic imaging. The images were acquired at the time of injection and one, six, and twenty-four hours later to analyze the trajectory, persistence, and distribution of the cells.

Results

The results were evaluated based on the uptake, persistence, variability, and distribution of the MSCs.

• The research found that both RLP techniques represented lower uptake, greater variability, poorer distribution, and lower persistence of MSCs.
• Results also indicated that the tourniquet used to perform RLP was either partially or wholly unsuccessful.
• The RLP performed on standing, sedated horses proved less efficient than procedures executed under general anesthesia.

Additionally, subcutaneous injections in the metacarpal area and coronary band resulted in a loss of MSCs to the general blood circulation, but showed no evidence of local migration of MSCs.

Conclusions

The research concluded that further study is needed to optimize the use of tourniquets in performing RLP for MSC administration in sedated, standing horses. Particularly, the issue of tourniquet failure needs to be addressed. Moreover, subcutaneous injections did not yield local migration of MSCs, a factor that needs to be looked into when considering potential applications of these methods.